Conventionally, modacrylic fibers composed of a modacrylic resin obtained by copolymerizing acrylonitrile and a vinyl chloride monomer have been used as flame-retardant materials or artificial hair while taking advantage of their characteristics of heat resistance and/or flame retardance. Since modacrylic resins have a decomposition starting temperature that is lower than their softening temperature, they are decomposed when being melt-processed. Usually, therefore, they are fiberized by a wet spinning method (Patent Documents 1 to 3). However, in the case of the wet spinning method, the drainage load is high and the cost of solvent recovery is high. Therefore, Patent Document 4 discusses melt spinning of modacrylic fibers.